Mixing apparatus and method



July 28, 1964 RElNBERG 3,142,478

MIXING APPARATUS AND METHOD Filed Jan. 30, 1959 4 Sheets-Sheet 1 FIG.I

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INVENTOR GUSTAVE REINBERG ATTORNEYS.

United States Patent 3,142,478 MIXING APPARATUS AND METHOD Gustave Reinberg', Landing, N.J., assignor to Freeport Sulphur Company, New York, N.Y., a corporation of Delaware Filed Jan. 30, 1959, Ser. No. 790,221 22 Claims. (Cl. 259-114) The present invention relates to metallurgical processes, and particularly to a new and improved method of, and apparatus for resuspending within a liquid, finely divided, small particles that have settled from a slurry of said particles and liquid.

In certain metallurgical recovery processes, slurries made up of water and suspended particles of ore must be handled. As an example, a serious problem arises in the handling of nickel sulfide slurries which are produced at the point of mining and which must be transported great distances, often overseas, to processing plants Where the initial step in the metallurgical recovery process requires the nickel sulfide particles to be suspended within Water in the form of the slurry produced at the site of the original mining.

Many attempts have been made in an eifort to overcome this problem, but with substantially no success. The power required to maintain the sulfide particles in suspension is exorbitant, amounting to something like 3 HR per 1,000 gallons of slurry. When it is considered that quantities of upwards of 300,000 gallons comprise a normal quantity for shipment, it becomes apparent that the power to maintain the slurry agitated would be prohibitive. Moreover, the large sizes of tanks required for economically handling the quantities of slurry involved create serious mechanical problems in the design of agitating equipment of the required dimensions and power output.

Permitting the slurry to remain unagitated during storage and en route with an idle agitator within the containers causes embedding of the particles around the agitator blade in such fashion as to make it practically impossible to restart the agitator blade When it is desired to cause resuspension of the particles within the liquid of the slurry.

Filtering the slurry, drying and packaging the precipitate involve an excessive amount of equipment, labor and loss of valuable materials within the slurry. Furthermore, upon arrival at the processing plant, the dry precipitate must be resuspended in water prior to the recovery processing thereof.

The principal object of this invention is to provide a method of, and an apparatus for delivering to a distant point a slurry of finely divided particles suspended within a liquid.

Another object of this invention is to provide such a method and apparatus that will entail a minimum of power requirements.

Another object of this invention is to provide an apparatus for accomplishing the desired results that will permit the solids settling out of the slurry and still require less power to resuspend them than would be required to maintain the slurry agitated to prevent such settling out of the particles.

Another object of this invention is to provide such an apparatus including a portable agitating assembly capable of being looked over a tank or container of slurry from which finely divided particles have settled, and a control system therefor that will cause the agitator of the assembly to progressively resuspend controlled quantities of the precipitated particles into the liquid thereabove.

Another object of this invention is to provide a design of agitating apparatus which is suitable for heavy-duty service in tanks of large diameter and depth requiring 3,142,478 Patented July 28, 1964 large diameter impellers, heavy rotating torque to supply large horsepowers at slow speeds, and long axial movement of impeller.

Another object of this invention is to provide such an agitating apparatus which is latched in its upper position when not being used, and is incapable of being released until supported by hydraulic means.

It has been found that the top layer of settled particles of a cake of precipitated nickel sulfide or the like can be resuspended in the liquid from which the particles have settled, by agitating the portion of said liquid in contact with the top layer of settled particle's. Then by progressively and in a controlled manner lowering the agitator blade or paddle, successive layers of such particles can be resuspended in the liquid until the entire mass is returned to its initial slurry condition.

In one aspect of the invention, a portable, structural steel supporting bridge may be formed in a manner to be mounted in position over a tank or container containing the slurry from which the solids have settled out into a cake of solids. The bridge structure may support driving motor means, which may be a plurality of symmetrically spaced motors, adapted to drive, through gear reduction units, a common ring gear that may be fixed to a main driving quill. In one form, motors may be diametrically spaced. The quill may be journaled in anti-friction bearings within a centrally disposed, hollow, cylindrical housing forming part of the bridge structure. The quill may include an elongated, split, cylindrical driving member having internal spline-like recesses for receiving shoe-like members on the periphery of an elongated, hollow cylinder that is adapted to be rotated by the quill and capable of axial movement. The lower end of the cylinder may be axially aligned with, and fixed to a shaft, on the lower end of which may be mounted a radial paddle or agitating blade. The upper end of the cylinder may be closed by a stuffing box through which may extend a rotatable but axially fixed, hollow, tubular piston rod which may be fixed at its upper end to a mounting flange that is in turn fixed to the split cylindrical driving member.

The lower end of the hollow, tubular piston rod may support a piston within the cylinder, and a hollow tube may extend from the bottom of the piston upwardly and concentrically with the hollow piston rod, providing an annular space therebetween. This tube may extend to the top of the piston rod and both its top end and that of the piston rod may be connected to a manifold mounted on, and rotatable with the mounting flange connected to the split cylindrical member of the driving quill. The manifold may be supplied with liquid under pressure from a hydraulic system through a revolving joint similar to the type known commercially as a Barco Revolving Joint."

In another aspect of the invention, a latching device may be mounted on, and rotatable with the split cylindrical driving member and cooperable with a ratchet element fixed to the top of the hollow, rotatable, axially movable cylinder. The latching means may be operated hydraulically, and so connected into the hydraulic system for reciprocating the cylinder and paddle that it will not be released until the pressure in the hydraulic system is sufficient to support thhe weight of the paddle and its driving structure.

In still another aspect of the invention, the hydraulic system may include means for supplying pressure liquid to the annular space between the hollow, cylindrical piston rod and the concentrically disposed tube extending therethrough, from which annular space it may exit to the space above the piston within the rotatable, axially movable cylinder, or through the concentric tube to the space below the piston within said cylinder. A flow control valve may be provided in the hydraulic system for varying the effectiveness of the supply pump within that portion of the system that is employed in lowering the paddle. In this way, a varying, controlled lowering of the paddle may be effected while still permitting maximum effectiveness of the supply pump in raising the paddle.

In another aspect of the invention, an electrical control circuit may be provided for controlling the operation of the hydraulic system. It may include means for stopping the paddle drive motors if a predetermined torque is encountered. It may include other means for bypassing the pressure liquid of the pump temporarily if a predetermined lesser torque is encountered so that should the flow control valve be set to permit a too rapid descent of the paddle, the system will automatically function to progressively lower the paddle at a rate responsive to the time required to cause resuspension of the settled particles at the top surface of the cake of precipitate.

The above, as well as other objects and novel features of the invention will become apparent from the following specification and accompanying drawings which are merely exemplary.

In the drawings:

FIG. 1 is an elevational view partially in section of a portable agitator to which the principles of the invention have been applied;

FIG. 1A is an enlarged partial, sectional elevational view of structure near the top of FIG. 1, but rotated through 90;

FIG. 2 is a sectional plan view, looking in the direction of the arrows and taken substantially along line 22 of FIG. 1;

FIG. 3 is a sectional plan view, looking in the direction of the arrows and taken substantially along line 33 of FIG. 1;

FIG. 4 is an enlarged sectional plan view, looking in the direction of the arrows and taken substantially along line 44 of FIG. 1;

FIG. 5 is a schematic view of the hydraulic circuit forming part of the invention;

FIG. 6 is an electrical diagram of the control circuit for the system; and

FIG. 7 is a more sophisticated showing of the schematic view of FIG. 5.

Referring to the drawings, and particularly to FIGS. 1, 2 and 3, the principles of the invention are shown as applied to a portable agitating mechanism including a bridge structure 10 of generally rectangular form. It is shown as being built up of structural steel plates including a top plate 11 to which is afiixed a tubular, centrally disposed housing 12 by suitable radially disposed plates 13 welded or otherwise fixed to the housing 12 and the plate 11. Suitable reinforcing plates 14, 15 and 16 are employed to provide ribs, all interconnected to the plate 11 and plates 13 to form a rigid supporting assembly.

A plate 17 is fixed to the plate 11 in spaced relation, providing a chamber 18 therebetween. The plate 17 is of less area than plate 11, providing flange-like means 19 extending beyond plate 17 for engaging supporting means (not shown) over a tank containing a slurry to be agitated.

A cylindrical housing 20 is fixed to the plate 17 by radial plates 21, and reinforcing plates 22, 23 and 24 (FIG. 3) are employed to provide a rigid structure, the whole providing means for supporting housing member 12 and 20 in aligned, spaced relation.

Drive motors 25 and 26 having integral speed-reducing boxes 27 and 28 are mounted on plate 11 in diametrical relation. An output shaft 29 and 30 of the boxes 27 and 28 supports spur gears 31 and 32 that mesh with a common ring gear 33 keyed to a driving quill 34 journaled in aligned anti-friction bearings 35 and 36 within the housings 20 and 12, respectively.

The quill 34 is keyed, or otherwise fastened, to a tubular member 37 which in turn may be keyed to a flanged collar 38. Bolted or otherwise fastened to the collar 38 is an elongated, vertically extending driving sleeve 39 that extends from the collar 38 upwardly to near the top of the agitating apparatus. Referring to FIG. 4, the sleeve 39 is shown as being formed of two semicircular halves 40 and 41, each having diametrically opposed recesses 42 and 43 extending throughout the longitudinal extent of the sleeve. The halves 40 and 41 are bolted together along longitudinally extending flanges 44, 45, 46 and 47. A mounting flange 48 is fixed to the top of sleeve 39. An elongated cylinder 49 is mounted within the sleeve 39 for reciprocable movement along the longitudinal axis of the sleeve. Referring to FIG. 1A, the cylinder 49, at its upper end, includes a stuffing box 50 that is bolted thereto and which includes 21 depending, cylindrical skirt 51 rigidly attached to the flange 50' of the stuifing box 50. The skirt 51 is keyed to cylinder 49 and includes diametrically opposed trunnions 51 for supporting shoes 51" adapted to ride within the longitudinally extending recesses 42 and 43 formed on the inner periphery of the driving sleeve 39. A gland 53 effectively closes the upper end of the cylinder 49.

The lower end of the cylinder 49 extends downwardly through cylinder 37 (FIG. 1) and is surrounded by guiding and sealing elements 54 and 55. A closure plate 56 is employed to close the lower end of cylinder 49, and a coupling 57 joins it to a drive shaft 53, to the lower end of which a paddle 59 including radial blades 60 is fixed.

A tubular piston rod 61 extends from within the interior of cylinder 49 upwardly through the stufling box 50 and is fixed to a manifold 62 that in turn is fixed to the mounting flange 48. A piston 63 is fixed to the lower end of the piston rod 61. A tube 64 extends interiorly and throughout the length of the piston rod 61, having its lower end opening into the cylinder 49 below piston 63, and forming with rod 61 an annular chamber 65 between the tube 64 and rod 61. The upper end of tube 64 is likewise connected to the manifold 62, and port 66 therein supplies liquid under pressure to the interior of tube 64, while a separate port 67 supplies liquid under pressure to the annular space 65 between the tube 64 and cylinder 61. A port 68 at the lower end of rod 61 that is connected to the piston 63 admits liquid from the annular space 65 to the cylinder 49 above the piston 63.

From the foregoing, it is evident that rotation of the motors 25 and 26 will drive quill 34 through gears 31, 32 and 33; that quill 34 drives split sleeve 39 through collar 38; that sleeve 39 in turn drives the cylinder 49 and paddle 59 through shoes 51" riding in recesses 42 and 43; and that piston rod 61, piston 63 and tube 64 are driven through the manifold 62. Since piston 63 is axially fixed, introduction of pressure liquid into cylinder 49 on opposite sides of piston 63 causes vertical reciprocation of cylinder 49 and with it paddle 59.

In order to lock the cylinder 49 and paddle 59 in their uppermost positions, a ratchet 69 is formed on the skirt 51 for cooperation with a pivotally mounted pawl 70. An arm 71 of pawl 70 extends between a spring pressed plunger 72 and a hydraulically operable piston 73 mounted in aligned relation within a housing 74 attached to the outer surface of the split sleeve 39. The plunger 72 normally urges the pawl 70 into cooperation with ratchet 69, and pressure liquid introduced onto the top of piston 73 turns pawl 70 in a counterclockwise direction to release cylinder 49 for downward movement. When this occurs, a gravity-operated pawl 75 engages pawl 70 to retain it in its unlatched position. The gravity-operated pawl 75 is provided with a protuberance 76 which, when engaged by the top of the stuffing box 50 upon cylinder 49 arriving at its uppermost position, releases pawl 70 so that the latter becomes effective by the action of spring plunger 72.

Pressure liquid is adapted to be supplied from a nonrotatable inlet to the rotatable manifold 62 through a revolving joint 77 of a commercial type, such as that known as a Barco Revolving Joint. It may include a port 78 that is in communication with a port 80 (FIG. 5) that connects to port 66 as well as to a port 81 leading to the top of piston 73. The joint 77 also includes another port 82 that communicates through a duct 83 (FIG. 1A) with a port 84 within manifold 62. The port 84 is connected to port 67 by a line that includes a check valve ill'ld bypass arrangement for a purpose to be described ater.

A hydraulic pump 85 includes an outlet which is connected to a line 86 having therein a check valve 87, said line 86 being connected to a relief line and valve 88. The line 86 leads to a four-way, shiftable control valve 89 having a lever 90 for operating it manually. With lever 90 in a central position, valve 89 is neutral (solid line position). In neutral, valve 89 blocks the flow of liquid through it, causing the liquid in line 86 to pass through relief line and valve 88 to sump. With lever 90 in its righthand position, valve 89 causes the flow of supply liquid to raise the cylinder 49; and in the lefthand position of lever 90, valve 89 causes the flow of liquid to lower cylinder 49 and paddle 59.

The line 86 is connected to a non-rotatable port 73 of joint 77. A line 91, connected to port 80 leads to port 81 on the top of the cylinder containing piston 73. Another line 92 leads from a port 93 in housing 74 to port 66 in manifold 62. A line 94 and check valve 95 connect line 91 and line 92. The construction is such that when it is desired to lower the cylinder 49 (lever 90 in its lefthand position), and should the oil in cylinder 49 above piston 63 have become depleted, the oil passes from line 86, through ports 78 and 80, through line 91 to the top of piston 73, but will not act on it; rather it bypasses through a line 96, a check valve 97, a line 98 to port 67 in manifold 62, thence to the annular space 65, thence through the port 68, filling the cylinder 49 above piston 63 and finally filling space 65 with oil. When this annular space 65 is filled, pressure builds up, causing piston 73 to be lowered, thereby releasing pawl 70. In this way, the cylinder 49 is supported by a column of oil in cylinder 49 above piston 63 before cylinder 49 will be released for downward movement. Resistance valve 99 prevents the escape of oil from the chamber in cylinder 49 above piston 63 unless the pressure in this space is greater than that necessary to support the vertically moving parts.

When the piston 73 moves downwardly, it opens port 93, permitting pressure liquid to flow through line 92 to port 66, thence through tube 64 to cylinder 49 below piston 63, thereby moving cylinder 49 downwardly. The oil in cylinder 49 above piston 63 is now at sutficient pressure to open resistance valve 99, and thus exhausts through port 68, annular space 65, port 67, line 98, through valve 99 which is now open, thence through a line 100 that is connected to port 84 in manifold 62, thence through duct 83 (FIG. 1A), port 82, a line 101, through a valve 102 and line 103 to sump.

The speed at which cylinder 49 may be lowered may be controlled by bleeding off the supply liquid from line 86 through a manually settable flow control valve 104 leading to sump. By adjusting valve 104, a predetermined rate of descent of the cylinder 49 and paddle 59 may be effected.

Moving lever 90 to the right causes pressure liquid from pump 85 to pass through line 103, line 101, port 82, port 84, line 100, thence through a free-flow check valve in resistance valve 99, line 98, port '67 to the annular space 65, thence through port 68 into cylinder 49 above piston 63, thereby moving cylinder 49 and paddle 59 upwardly. The oil in cylinder 49 beneath piston 63 passes upwardly through tube 64, past port 66, check valve 95, line 94, thence through line 91, past port 80, port 78, and through line 86 and valve 89 to sump. Since the upward travel of the paddle 59 is preferably as rapid as possible, no flow control is provided in this portion of the circuit.

Referring to FIG. 6, a cross-the-line conventional wiring diagram is employed to disclose the electrical control circuit. In this diagram, normally open contacts are identified as two short, parallel lines, while normally closed contacts are shown as two short, parallel lines with a diagonal line thereacross. The following text will include numerals in parentheses which will refer to the ordinates on the righthand side of FIG. 6.

Closing the ST starting switch (1) energizes the relay coils 25M and 26M (1, 2), which closes normally open contacts 25M- 1 and 26M-1 (2) for holding the relay coils 25M and 26M energized after release of the ST starting switch. Energizing relay coils 25M, 26M closes contacts 25M-2; 25M-3; 25M-4; 26M-2; 26M-3 and 26M 4 in the circuits for motors 25 and 26, thereby starting the rotation of the cylinder 49 and paddle 59.

The normally closed contacts 27-1 and 28-1 (2) are torque responsive switches that are set to open if the speed-reducing units 27 and 28 encounter 150 percent of normal motor torque.

The contacts 105 (4) and 105-1 (5) are, respectively, normally open and closed when the lever is in either its right or lefthand position, and are normally closed and open, respectively, when the lever 90 is in its neutral position. This ensures that the lever 90 is in neutral before the relay 85M can be energized by closing the pump starting switch ST (4). Energizing the relay 85M (4) closes contacts 85M-1 (3) for holding the circuit after opening of the contacts when lever 90 is moved from its neutral position. Also, energizing relay 85M closes contacts 85M-2, 85M-3 and 85M-4 for connecting the pump motor 85 into its operating circuit.

Moving lever 90 to the right causes the cylinder 49 and paddle 59 to rise, as previously explained. When it reaches its topmost position, a pressure switch PS-R (5) closes, which energizes TD time delay relay coil (5). After a preset time delay of, for instance, five to ten seconds, contacts TD1 (4) open, thereby stopping the pump 85. However, the operator may center the control lever 90 during this delay period which resets the TD relay (5), maintaining the pump 85 in operation, if such is desired in a special case.

Movement of the lever 90 to the left will cause lowering of the paddle 59 at a rate depending upon the setting of valve 104 as previously explained. However, should the descent be too rapid for the rate at which the settled particles are resuspended, then contacts 27-2 and 28-2 (10, 12) will close. They may be set to close at approximately percent of normal torque of motors 25 and 26. Closing either or both of these contacts energizes a relay coil 106 (9), thereby to open a normally closed bypass valve 107 (FIG. 5) to bypass the entire output of pump 85 to sump, thereby temporarily stopping the downward movement of the paddle 59 until the torque falls below 120 percent of normal motor torque, when the descent of paddle 59 is resumed.

This bypass valve 107 may also be operated when the PSL switch (7) closes after the paddle 59 is at the bottom of its travel. Closing PS-L switch (7) energizes relay coil R (7) thereby closing R-1 and R-2 switches (8, 9). Closing the R-l switch opens the bypass valve 107 and also lights a light R (11) indicating that the bypass valve 107 is open.

It should be apparent that details of construction can be varied without departing from the spirit of the invention except as defined in the appended claims.

What is claimed is:

1. In an agitator, a supporting frame; a rotatablememb'er journaled in said frame; driving means mounted on said frame for driving said rotatable member; a torque transmitting tube connected to said rotatable member; cylinder means and piston means mounted within said torque transmitting tube and rotatable therewith, but one of said means being axially movable relatively thereto; an impeller fixed to one of said means; and pressure fluid means independent of, and simultaneously operable with the rotation of said impeller for providing relative axial movement between said means.

2. In an agitator, a supporting frame; a rotatable member journaled in said frame; driving means mounted on said frame for driving said rotatable member; a two-part torque transmitting tube connected to said rotatable mem ber; cylinder means and piston means mounted within said torque transmitting tube and rotatable therewith, but one of said means being axially movable relatively thereto; an impeller fixed to one of said means; and pressure fluid means independent of, and simultaneously operable with the rotation of said impeller for providing relative axial movement between said means.

3. In an agitator, a supporting frame; a rotatable member journaled in said frame; driving means mounted on said frame for driving said rotatable member; a torque transmitting tube connected to said rotatable member; cylinder means and piston means mounted within said torque transmitting tube and rotatable therewith; hearing shoe means between one of said cylinder and piston means and said torque transmitting tube; an impeller fixed to one of said cylinder and piston means; and pressure fluid means independent of, and simultaneously operable with the rotation of said impeller for providing relative axial movement between said cylinder and piston means.

4. In an agitator, a supporting frame; a rotatable member journaled in said frame; driving means for driving said rotatable member; a torque transmitting tube connected to said rotatable member; cylinder means and piston means mounted within said torque transmitting tube and rotatable therewith; trunnioned journaled shoe means between one of said cylinder and piston means and said torque transmitting tube; an impeller fixed to one of said cylinder and piston means; and pressure fluid means independent of, and simultaneously operable with the rotation of said impeller for providing relative axial movement between said cylinder and piston means.

5. In an agitator, a supporting frame; a rotatable member journaled in said frame; driving means mounted on said frame for driving said rotatable member; a torque transmitting tube connected to said rotatable member; cylinder means and piston means mounted within said torque transmitting tube and rotatable therewith, but one of said means being axially movable relatively thereto; a hollow piston rod connected to said piston; a tube within and concentric with said piston rod; means estab lishing communication between the annular space formed by said tube and hollow piston rod with said cylinder on one side of said piston; means for establishing communication between the interior of said tube and said cylinder on the other side of said piston; and a manifold for supplying pressure fluid to the interior of said tube and to the annular space formed by said tube and said hollow piston rod.

6. In an agitator, a supporting frame; a rotatable member journaled in said frame; simultaneously operable, diametrically disposed driving means mounted on said frame for driving said rotatable member and mounted on opposite sides of the axis of rotation of said rotatable member; a torque transmitting tube connected to said rotatable member; cylinder means and piston means mounted within said torque transmitting tube and rotatable therewith, but one of said means being axially movable relatively thereto; an impeller fixed to one of said cylinder and piston means; and pressure fluid means independent of, and simultaneously operable with the rotation of said impeller for providing relative axial movement between said cylinder and piston means.

7. Apparatus for causing the resuspension of settled particles within a slurry comprising in combination, an impeller; means for supporting said impeller within a layer of supernatant liquid in closely spaced relation to the top surface of the mass of settled particles; means for rotating said impeller; means for feeding said impeller downwardly at a predetermined rate; and torque responsive means for controlling said feeding means independently of said rotating means in the event said rate of feed exceeds the rate of particle resuspension.

8. Apparatus for causing the resuspension of settled particles within a slurry comprising in combination, an impeller; means for supporting said impeller within a layer of supernatant liquid in closely spaced relation to the top surface of the mass of settled particles; means for rotating said impeller; means for feeding said impeller downwardly at a predetermined rate; and torque responsive means for temporarily interrupting said feeding means independently of said rotating means in the event said rate of feed exceeds the rate of particle resuspension.

9. Apparatus for causing the resuspension of settled particles within a slurry comprising in combination, an impeller; a cylinder for supporting said impeller within a layer of supernatant liquid in closely spaced relation to the top surface of the mass of settled particles; means for rotating said cylinder; an axially fixed piston within said cylinder; means independent of the rotation of said cylinder for supplying pressure liquid to each side of said piston within a circuit to thereby support said cylinder; means for exhausting the liquid on a first side of said piston while supplying pressure liquid to the second side of said piston to effect the movement of said cylinder and impeller in a direction away from said settled particles at a relatively rapid rate; and means for exhausting the pressure liquid from said second side of said piston while supplying said pressure liquid to the first side of said piston at a predetermined rate to cause movement of said cylinder and impeller at a relatively slow rate in a direction toward said settled particles.

10. Apparatus for causing the resuspension of settled particles within a slurry comprising in combination, an impeller; a cylinder for supporting said impeller within a layer of supernatant liquid in closely spaced relation to the top surface of the mass of settled particles; means for rotating said cylinder; an axially fixed piston within said cylinder; means for supplying pressure liquid to each side of said piston within a circuit to thereby sup port said cylinder; means for exhausting the liquid on a first side of said piston while supplying pressure liquid to the second side of said piston to effect the movement of said cylinder and impeller in one direction at a relatively rapid rate; means for exhausting the pressure liquid from said second side of said piston while supplying said pressure liquid to the first side of said piston at a predetermined rate to cause movement of said cylinder and impeller at a relatively slow rate in the opposite direction; and means responsive to a predetermined torque encountered in rotating said cylinder for temporarily interrupting the last mentioned supply of said pressure liquid to said first side of said piston.

11. Apparatus for causing the resuspension of settled particles within a slurry comprising in combination, an impeller; a cylinder for supporting said impeller within a layer of supernatant liquid in closely spaced relation to the top surface of the mass of settled particles; means for rotating said cylinder; an axially fixed piston within said cylinder; means for supplying pressure liquid to each side of said piston within a circuit to thereby support said cylinder; latch means for locking said cylinder in its uppermost position; means for releasing said latch means; means for exhausting the liquid on a first side of said piston while supplying pressure liquid to the second side of said piston to effect the movement of said cylinder and impeller in one direction at a relatively rapid rate; means for exhausting the pressure liquid from said second side of said piston while supplying said pressure liquid to the first side of said piston at a predetermined rate to cause movement of said cylinder and impeller at a relatively slow rate in the opposite direction; and means responsive to a predetermined pressure on said second side of said piston for rendering said releasing means effective.

12. Apparatus for causing the resuspension of Settled particles within a slurry comprising in combination, an impeller; a cylinder for supporting said impeller within a layer of supernatant liquid in closely spaced relation to the top surface of the mass of settled particles; means for rotating said cylinder; an axially fixed piston within said cylinder; means for supplying pressure liquid to each side of said piston within a circuit to thereby support said cylinder; latch means for locking said cylinder in its uppermost position; means for releasing said latch means; means for exhausting the liquid on a first side of said piston while supplying pressure liquid to the second side of said piston to effect the movement of said cylinder and impeller in one direction at a relatively rapid rate; means for exhausting the pressure liquid from said second side of said piston while supplying said pressure liquid to the first side of said piston at a predetermined rate to cause movement of said cylinder and impeller at a relatively slow rate in the opposite direction; means responsive to a predetermined pressure on said second side of said piston for rendering said releasing means effective; and means responsive to a predetermined torque encountered in rotating said cylinder for temporarily interrupting the last mentioned supply of said pressure liquid to said first side of said piston.

13. In an agitator, a supporting frame; a vertically disposed, rotatable driving quill journaled in bearings within said frame; a ring gear fixed to said quill; motor means mounted on said frame; intermeshing gearing means between said motor means and said ring gear; a torque transmitting tube fixed to said quill and extending vertically upwardly to near the top of said agitator; longitudinally extending grooves along the inner surface of said torque tube; a cylinder within said torque tube; means on said cylinder for cooperating with the grooves within said torque tube; means for moving said cylinder axially within said torque tube comprising a rotatable, axial fixed piston rod extending into said cylinder and connected to said torque tube at the top thereof; a piston on said rod; an impeller fixed to the lower end of said cylinder; and means for supplying pressure fluid to the interior of said cylinder on opposite sides of the piston therein, whereby said cylinder is rotated by said quill while axially movable within said torque tube.

14. In an agitator, a supporting frame; a vertically disposed, rotatable driving quill journaled in bearings within said frame; a ring gear fixed to said quill; motor means mounted on said frame; intermeshing gearing means between said motor means and said ring gear; a two-part torque transmitting tube fixed to said quill and extending vertically upwardly to near the top of said agitator; longitudinally extending grooves along the inner surface of said torque tube; a cylinder within said torque tube; means on said cylinder for cooperating with the grooves within said torque tube; means for moving said cylinder axially within said torque tube comprising a rotatable, axially fixed piston rod extending into said cylinder and connected to said torque tube at the top thereof; a piston on said rod; an impeller fixed to the lower end of said cylinder; and means for supplying pressure fluid to the interior of said cylinder on opposite sides of the piston therein, whereby said cylinder is rotated by said quill while axially movable within said torque tube.

15. In an agitator, a supporting frame; a vertically dis posed, rotatable driving quill journaled in bearings within said frame; a ring gear fixed to said quill; motor means mounted on said frame; intermeshing gearing means between said motor means and said ring gear; a torque transmitting tube fixed to said quill and extending vertically upwardly to near the top of said agitator; longitudinally extending grooves along the inner surface of said torque tube; a cylinder within said torque tube; bearing shoe means on said cylinder for cooperating with the grooves within said torque tube; means for moving said cylinder axially within said torque toube comprising a 10 rotatable, axially fixed piston rod extending into said cylinder and connected to said torque tube at the top thereof; a piston on said rod; an impeller fixed to the lower end of said cylinder; and means for supplying pressure fluid to the interior of said cylinder on opposite sides of the piston therein, whereby said cylinder is rotated by said quill while axially movable within said torque tube.

16.- In an agitator, a supporting frame; a vertically disposed, rotatable driving quill journaled in bearings within said frame; a ring gear fixed to said quill; motor means mounted on said frame; intermeshing gearing means between said motor means and said ringgear; a two-part torque transmitting tube fixed to said quill and extending vertically upwardly to near the top of said agitator; longitudinally extending grooves along the inner surface of said torque tube; a cylinder within said torque tube; trunnioned journaled shoe means on said cylinder for cooperating with the grooves within said torque tube; means for moving said cylinder axially within said torque tube comprising a rotatable, axially fixed piston rod extending into said cylinder and connected to said torque tube at the top thereof; a piston on said rod; an impeller fixed to the lower end of said cylinder; and means for supplying pressure fluid to the interior of said cylinder on opposite sides of the piston therein, whereby said cylinder is rotated by said quill while axially movable within said torque tube.

17. In an agitator, a supporting frame; a vertically disposed, rotatable driving quill journaled in bearings within said frame; a ring gear fixed to said quill; motor means mounted on said frame; intermeshing gearing means between said motor means and said ring gear; a torque transmitting tube fixed to said quill and extending vertically upwardly to near the top of said agitator; longitudinally extending grooves along the inner surface of said torque tube; a cylinder within said torque tube; an impeller fixed to the lower end of said cylinder; means on said cylinder for cooperating with the grooves within said torque tube; means for moving said cylinder axially within said torque tube comprising a rotatable, axially fixed hollow piston rod extending into said cylinder and connected to said torque tube at the top thereof; a piston on said rod; a tube extending along the central longitudinal axis of said hollow piston rod and having its one end open to said cylinder on one side of said piston; means establishing communication between the annular space formed by said tube and hollow piston rod with said cylinder on the opposite side of said piston; and a manifold for supplying pressure fluid to the interior of said tube and to the annular space formed by said tube and hollow piston rod, whereby said cylinder is rotated by said quill while axially movable within said torque tube.

18. In an agitator, a supporting frame; a vertically disposed, rotatable driving quill journaled in bearings within said frame; a ring gear fixed to said quill; diametrically disposed motor means mounted on said frame and located on opposite sides of the axis of rotation of said quill; intermeshing gearing means between said motor means and said ring gear; a torque transmitting tube fixed to said quill and extending vertically upwardly to near the top of said agitator; longitudinally extending grooves along the inner surface of said torque tube; a cylinder within said torque tube; means on said cylinder for cooperating with the grooves within said torque tube; means for moving said cylinder axially within said torque tube comprising a rotatable, axially fixed piston rod extending into said cylinder and connected to said torque tube at the top thereof; a piston on said rod; an impeller fixed to the lower end of said cylinder; and means for supplying pressure fluid to the interior of said cylinder on opposite sides of the piston therein, whereby said cylinder is rotated by said quill while axially movable within said torque tube.

19. In an agitating apparatus, a bridge structure; a container lockably receiving said bridge structure on the top thereof; a rotatable shaft supported by said bridge structure; an impeller on said shaft; driving means for rotating said shaft; hydraulic means adapted to support said shaft and to lower and raise said shaft while maintaining said driving means effective at all times; releasable means for mechanically locking said shaft in its uppermost position; and means for ensuring the support of said shaft by said hydraulic means before said releasable means is released.

20. In an agitating apparatus, a bridge structure; a container lockably receiving said bridge structure on the top thereof; a rotatable shaft supported by said bridge struc ture; an impeller on said shaft; driving means for rotating said shaft; means for raising and lowering said shaft while maintaining said driving means effective at all times, said means comprising an hydraulic circuit adapted to cause raising and lowering of said shaft; releasable means for mechanically locking said shaft in its uppermost position; means for ensuring the support of said shaft by said hydraulic means before said releasable means is released; and means within the lowering portion of said circuit for controlling the rate of lowering of said shaft.

21. The method of resuspending settled particles within a slurry which comprises the steps of operating an agitating means for agitating the supernatant liquid directly in contact with the top of the settled particles, to cause the topmost particles to become resuspended within said supernatant liquid thereby lowering the level of said settled particles; and progressively moving said agitating means downwardly to maintain substantially the same agitating effect of the supernatant liquid directly in contact with the receding top of said settled particles.

22. The method of resuspending settled particles within a slurry which comprises the steps of operating an agitating means for agitating the supernatant liquid di rectly in contact with the top of the settled particles; to cause the topmost particles to become resuspended within said supernatant liquid thereby lowering the level of said settled particles; and progressively moving said agitating means downwardly at a rate responsive to the torque encountered by said agitating means to maintain substantially the same agitating effect of the supernatant liquid directly in contact with the receding top of said settled particles.

References Cited in the file of this patent UNITED STATES PATENTS 2,262,412 Weinig Nov. 11, 1941 2,291,874 Campbell Aug. 4, 1942 2,322,720 Scott et al June 22, 1943 2,330,895 Judge Oct. 5, 1943 2,386,006 Satford Oct. 2, 1945 2,528,051 Graner Oct. 31, 1950 2,553,958 Chelminski et al May 22, 1951 2,585,006 Graner et al Feb. 12, 1952 2,589,298 Scott Mar. 18, 1952 2,703,557 Polki Mar. 8, 1955 2,816,219 Ihrig Dec. 10, 1957 2,837,215 Chelrninski June 3, 1958 2,892,620 Johnston June 30, 1959 2,898,094 ONeill Aug. 4, 1959 FOREIGN PATENTS 468,172 Germany Nov. 8, 1928 UNITED STATES PATENT OFFICE.

CERTIFICATE OF CORRECTION Patent No, 3,142,478 July 28 1964 Gustave Reinberg It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

In the drawings, Sheet 3, strike out the drawing labeled "FIG, '5"; Sheet 4, "FIG. 7" should be renumbered as FIG. 5

--; column 2, line 62, for "thhe" read the column 3, lines 42 and 43, strike out "FIG 7 is a more sophisticated showing of the schematic view of FIG. 5, column 4, line 15, for "51" read 51 column 9, line 75, for "toube" read tube column 12, list of References Cited under "UNITED STATES- PATENTS" add the following reference: I

2,906, 248 Pera s- Sept 1959 (SEAL) Signed and sealed this 12th y; 9 y 650 Attest:

ERNEST W. SWIDER EDWARD J.- BRENNER A'Itcsting Officer Commissioner of Patents 

1. IN AN AGITATOR, A SUPPORTING FRAME; A ROTATABLE MEMBER JOURNALED IN SAID FRAME; DRIVING MEANS MOUNTED ON SAID FRAME FOR DRIVING SAID ROTATABLE MEMBER; A TORQUE TRANSMITTING TUBE CONNECTED TO SAID ROTATABLE MEMBER; CYLINDER MEANS AND PISTON MEANS MOUNTED WITHIN SAID TORQUE TRANSMITTING TUBE AND ROTATABLE THEREWITH, BUT ONE OF SAID MEANS BEING AXIALLY MOVABLE RELATIVELY THERETO; AN IMPELLER FIXED TO ONE OF SAID MEANS; AND PRESSURE FLUID MEANS INDEPENDENT OF, AND SIMULTANEOUSLY OPERABLE WITH THE ROTATION OF SAID IMPELLER FOR PROVIDING RELATIVE AXIAL MOVEMENT BETWEEN SAID MEANS. 